Hard disk drive with reduced power consumption, related data processing apparatus, and I/O method

ABSTRACT

A hard disk drive is disclosed and related methods of reading/writing data are disclosed. The hard disk drive includes a disk serving as a main data storage medium, and first and second buffers storing data to be stored on the disk, as well as a controller defining a data I/O path in relation to a detected operating state of the hard disk drive.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate to a data storage device. Moreparticularly, embodiments of the invention relate to a hard disk drivewith reduced power consumption, a data processing apparatusincorporating the hard disk drive, and a related data input/output (I/O)method.

2. Description of the Related Art

With the advent of the information society, the amount of dataindividuals need to store and carry has increased dramatically. Thisneed drives a continuing demand for data storage media. Various personaldata storage devices have been developed to meet this demand. Oneexample of a data storage device is the hard disk drive (HDD). The HDDis widely used because of its high storage density, high datatransmission rate, rapid data access time, and low price. Technically, aHDD is a device that controls the position of a storage disk (i.e., theactual hard disk) during read and write operations directed to datastored on the disk. However, since the HDD and the disk are integratedin a single unit, the term “HDD” is generally understood to include boththe hard disk and its drive.

The record-type hard disk contained in the conventional HDD ismaintained in an internal vacuum space isolated from the externalenvironment. A Read/Write (R/W) head writes data to and reads data fromthe disk. A mechanical arm assembly moves the R/W head across thesurface of the disk. The conventional disk includes at least onealuminum plate coated with magnetic material. This combination serves asthe main data storage medium. The aluminum plate is also called a“platter”. The structure of a conventional HDD is disclosed, forexample, in U.S. Pat. No. 4,638,383, the subject matter of which isincorporated herein by reference.

HDDs may be classified into integrated drive electronics (IDE) type HDDsand small computer system interface (SCSI) type HDDs according to theirrespective interface types. The IDE type HDD includes an installedcontroller. Accordingly, unlike the SCSI type HDD, the IDE type HDD doesnot need a separate extension card. The IDE type HDD is also referred toas an advanced technology attachment (ATA). The ATA is a formalinterface name defined by the Small Form Factor (SFF) Committee.Recently, a serial-ATA interface defining serial data transmissions hasbeen incorporated into HDD devices.

Contemporary HDDs are mounted not only in desk top computers, but alsoin mobile devices having various data processing functions, such as anotebook computers, an MP3 players, cellular phones, personal digitalassistants (PDAs), and GPS navigators. Such mobile devices draw powerfrom a finite power source such as a battery. Accordingly, when thestored energy of the battery is expended, the mobile device will notoperate. Thus, power consumption for such mobile devices is anever-present design consideration.

Moderating power consumption by mobile device is a difficult task sinceoverall processing speeds are increasing and the mobile devise arerequired to perform an ever increasing numbers of tasks. Miniaturizationof components has helped reduce power consumption. For example, thedevelopment of the system on chip (SOC) technology has reduced totalpower consumption, but the ratio of total power consumption by themobile device to power consumption by the constituent HDD has actuallyincreased. Accordingly, further efforts are required to minimize thepower consumption of data storage devices, such as HDDs, incorporated inmobile devices.

SUMMARY OF THE INVENTION

Embodiments of the invention provides an apparatus and related methodadapted to further reduce the power consumption of a data storage device(e.g., a hard disk drive), and thereby extend the battery operating lifeof a mobile device. In one related aspect, embodiments of the inventionprovide an apparatus and related method adapted to define an efficientdata I/O path in accordance with various operating state for the datastorage device.

Thus, in one embodiment, the invention provides a hard disk drivecomprising; a disk, a first buffer adapted to temporarily store data tobe stored on the disk, a second buffer adapted to store data receivedfrom at least the first buffer, and a controller adapted to provide thedata temporarily stored in the first buffer to at least one of the diskand the second buffer in accordance with an operating state for thedisk.

In another embodiment, the invention provides a data processingapparatus comprising; a host adapted to generate a write request and aread request, and a hard disk drive adapted to write data in response tothe write request and read data in response to the read request througha normal data path or a bypass data path in accordance with an operatingstate for the hard disk drive. The hard disk drive may comprise; a disk,a first buffer adapted to temporarily store data to be stored on thedisk, a second buffer adapted to store data received from at least thefirst buffer, and a controller adapted to provide the data temporarilystored in the first buffer to at least one of the disk and the secondbuffer in accordance with an operating state for the disk.

In yet another embodiment, the invention provides a method for writingdata to and reading data from a hard disk drive comprising a disk, themethod comprising; storing data received from a host in a first buffer,detecting an operating state for the disk, and storing the data in thefirst buffer in at least one of a second buffer and the disk inaccordance with the detected operating state.

In still another embodiment, the invention provides a method ofreading/writing data, the method comprising; generating a dataread/write request in a host, and reading the data from or writing thedata to a hard disk drive in response to the read/write request, whereinthe data is read from or written to the hard disk drive through a normaldata path or a bypass data path in accordance with an operating state ofthe hard disk drive.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the invention are described with reference to theaccompanying drawings, in which:

Figure (FIG.) 1 is a block diagram of a data processing apparatusaccording to an embodiment of the invention;

FIG. 2 is a state diagram further illustrating operation of the HDDillustrated in FIG. 1;

FIGS. 3 and 4 are diagram comparing a stage change for a conventionalHDD wherein a data write/read request is repeatedly generated from ahost with a similar stage change for a HDD according to an embodiment ofthe invention;

FIG. 5 is a graph illustrating power consumption for the HDD illustratedin FIG. 3;

FIG. 6 is a graph illustrating power consumption for the HDD illustratedin FIG. 4;

FIG. 7 is a block diagram of an HDD according to one embodiment of theinvention;

FIG. 8 is a block diagram further illustrating an HDD controller, suchas the incorporated in the HDD shown in FIG. 7; and

FIG. 9 is a flowchart illustrating a process of inputting data to andoutputting data from a HDD according to an embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in some additional detail to embodiments ofthe present invention. However, the invention is not limited to only theembodiments described.

According to one embodiment of the invention, a HDD comprises a diskserving as a main data storage medium, first and second buffers adaptedto temporarily store data to be stored on the disk, and a controlleradapted to provide data input to the first buffer to one of either thedisk or the second buffer in accordance with the operating state of thedisk. In this regard, the second buffer stores part of data to be storedon the disk, and simultaneously provides the stored data to the disk.Accordingly, it is possible to reduce the occurrence ratio of an activestate relative to the overall operating state for the HDD, wherein theHDD consume a relatively large amount of power during the so-called“active state”. By reducing the occurrence ration power consumption bythe HDD is significantly reduced for data processing apparatusesincorporating the HDD. In one more specific embodiment, the secondbuffer is implemented using a nonvolatile memory, thereby providing anexcellent data recoverability.

FIG. 1 is a block diagram illustrating a data processing apparatus 300according to one embodiment of the invention, and more specifically aportable or mobile data processing apparatus 300 incorporating a harddisk drive (HDD) 200.

Referring to FIG. 1, data processing apparatus 300 may be divided intotwo parts; a host 100 and hard disk drive (HDD) 200. Host 100 generallycomprises a central processing unit (CPU) 110, a display 120, a battery130, and a key input unit 140. Host 100 and HDD 200 are conventionallyconnected via a bus 10. Examples of an interface between the host 100and the HDD 200 include an IDE interface, an SCSI interface, an ATAinterface, and serial-ATA interface.

Referring to FIG. 7 for the moment, HDD 200 comprises a disk 270 adaptedto store data and flash memory 250 adapted to serve as an intermediatedata storage medium. Flash memory 250 stores part of data to be storedin HDD 200, and simultaneously provides the stored data to HDD 200.Flash memory 250 may be implemented using conventional nonvolatilememory devices that retain written (or programmed) data within internalmemory cell even when power to the memory is turned off. Accordingly,flash memory 250 has a better data recoverability than other forms ofvolatile memory. However, various nonvolatile memories other than flashmemory may also be used as an intermediate data storage medium withinHDD 200. However, in one embodiment of the invention flash memory 250comprises NAND-type flash memory capable of performing a high-speedprogram/erase operations. This embodiment enables HDD 200 tocollectively and simultaneously process data request from host 100. Forexample, a data write operation and a data read operation may besimultaneously processed, thereby reducing the power consumed by HDD 200and, therefore, data processing apparatus 300.

FIG. 2 is a state diagram illustrating one exemplary set of operatingstates for HDD 200. The operating states are defined in relation topower management states (and, optionally, related power managementstandards) for HDD 200. The advanced power management (APM) standard andthe advanced configuration and interface (ACPI) standard are two readyexamples.

The exemplary operating states for HDD 200 and power consumptionassociated with each operating state will now be described withreference to FIG. 2. Referring to FIG. 2, four operating states aredefined for HDD 200, including; an active state, a standby state, anidle state, and a sleep state. In great measure, the operating statesfor HDD 200 can be regarded as the operating states for disk 270.

In the active state, HDD 200 may perform a data write operation, a dataread operation, and a data seek operation in response to commandsreceived from host 100. The active state typically consumes “full power”ranging from 2 to 2.5 W.

HDD 200 enters the idle state after about five seconds following thecompletion of one or more data write operation(s), data readoperation(s), and data seek operation(s) performed during an activestate. In the idle state, HDD 200 waits for a new command from host 100after executing all received command(s). In the idle state, a disk arm(not illustrated) is moved to a parking position and a servo trackingfunction is turned OFF. Under these conditions, since an interfaceroutine between host 100 and HDD 200 remains in a ready state, HDD 200can return to the active state within a very short period of time (e.g.,about 40 msec). Power consumed in the idle state is generally less than1 W.

In the standby state, most components within HDD 200, including itsspindle motor, are powered OFF. Under these conditions, it typicallytakes between 1.5 and 5 seconds for HDD 200 to return to the activestate. Power of about 0.3 W is consumed in the standby state.

In the sleep state, all components within HDD 200, other than componentsprocessing a wake-up command received host 100, are powered OFF.Accordingly, it takes a relatively long time (e.g., more than 5 seconds)for HDD 200 to return to the active state from the sleep state. Power ofabout 0.1 W is consumed in the sleep state.

Typical power consumption for HDD 200 in each of the foregoing operatingstates is summarized below in Table 1. (The power consumption figurescontained in Table 1 were developed by examining a 2.5″ HDD, modelMHT20AH manufactured by Fujitsu). TABLE 1 Operating State Spin-up ActiveIdle Standby Sleep Power 5 W (Max) 2.3 W 0.85 W 0.25 W 0.1 W Consumption

From the foregoing it can be understood that as the occurrence ratio ofthe active state to the overall operating state of HDD 200 increases,the total power consumed by data processing apparatus 200 incorporatingHDD 200 will increase. Also, as the respective occurrence ratios of thestandby state or the sleep state to the overall operating state of HDD200 increase, the total power consumed by data processing apparatus 200will decrease.

Thus, the power consumption of HDD 200 is closely related to theoccurrence frequencies of the respective operating states. By reducingthe occurrence frequency of the active state, power consumption for HDD200 may be reduced. The relationship between the occurrence frequency ofthe active state and the power consumption for HDD 200 will now bedescribed in some additional detail.

FIG. 3 is a diagram illustrating a stage change for a conventional HDDwhen a data write/read request is repeatedly generated by host 100. FIG.4 is a diagram illustrating a stage change for a HDD designed inaccordance with an embodiment of the invention and operating in responseto similar data write/read request from host 100. FIG. 5 is a graphillustrating power consumption for the conventional HDD. FIG. 6 is agraph illustrating power consumption for the HDD designed in accordancewith an embodiment of the invention.

Referring to FIGS. 3 and 5, it is apparent that power consumption forthe respective HDDs is actually determined according to the operatingstates of the disk. Whenever a data write/read request is generated byhost 100, the conventional HDD enters the active state. Whenever the HDDenters the active state, a full-power cycle consumes about 2.5 W over apredetermined period of operating time. Accordingly, even when the HDDprocesses a small amount of data, it consumes full power over the entirepredetermined period of time. During a complete cycle through which theconventional HDD transitions from the active state to the idle state tothe standby state, an average power of 2.0 W is consumed.

Referring now to FIGS. 4 and 6, whenever a data write/read request isgenerated by host 100, HDD 200 performs the corresponding write/readoperation using flash memory 250, instead of writing data into andreading data from disk 270. However, once flash memory 250 is full, thedata stored in flash memory 250 is transferred to disk 270 which servesas a “main memory” in relation to flash memory 250 which serves as a“temporary memory.”

But until flash memory 250 is full, actual write/read operations to/fromHDD 200 are performed using only flash memory 250. In contrast, disk 270of HDD 200 may remain in the standby state. That is, upon receiving areset command (CMD), HDD 200 transitions to the standby state and flashmemory 250 performs the data input/output operations. Accordingly, it ispossible to reduce the occurrence ratio of the active state and therebyreduce the power consumption of the data processing apparatusincorporating HDD 200. Experimental results show that under theforegoing assumptions HDD 200 enters the active state about once everyten minutes on average. Under these conditions, the average powerconsumption for HDD 200 falls to a mere 0.3 W, or about 6.67% of thepower consumption by the conventional HDD.

Thus, one principle established from the foregoing generally suggeststhat a data write request from host 100 should be executed by firstusing flash memory 250 rather than disk 270. However, it is often rathermore efficient to directly write data to disk 270 instead of writing itto flash memory 250. For example, where HDD 200 is already in the activestate and host 100 make a write request, data may be efficiently writtendirectly to disk 270. Additionally, after a direct write operation todisk 270, it may also be prudent to store all the accumulated data inflash memory 250 to disk 270. Other examples of circumstances where itis more efficient to directly write data to disk 270 include; a request(e.g., a cache flush CMD) by host 100 to flush the data stored in flashmemory 250 to disk 270 , or a data write request for a data block havinga size greater than the remaining capacity of flash memory 250.Hereafter, an operation directly writing data to disk 270 in response toa host device request will be termed a “bypass write operation.” By wayof distinction, an operation writing data to disk 270 through flashmemory 250 will be termed a “normal write operation.”

Similarly, another principle established from the foregoing suggeststhat a read request from host 100 should be executed by first accessingflash memory 250 rather than disk 270. However, where HDD 200 is alreadyin the active state, or where the requested read data do not stored inflash memory 250, the request data should be directly executed usingdisk 270. An operation directly reading requested data from disk 270will be termed a “bypass read operation.” An operation reading requesteddata from flash memory 250 will be termed a “normal read operation.”

FIG. 7 is a block diagram for a HDD 200 according to one embodiment ofthe present invention. Referring to FIG. 7, HDD 200 comprises a HDDcontroller 210, a (first) buffer 230, a (second buffer) flash memory250, and a disk 270. Buffer 230 serves as a hard disk cache storing datareceived from host 100. Generally, in order to reduce a differencebetween the rotation speed of the disk 270 and the speed of datainterface with host 100, HDD 200 includes buffer 230 performing a cachefunction. Buffer 230 may be implemented using a synchronous dynamicrandom access memory (SDRAM) adapted to high-speed data input/outputoperations.

Whenever data are received from host 100, HDD 200 store the data inflash memory 250. Thereafter, when flash memory 250 is full, the storeddata is simultaneously transferred to disk 270. However, when HDD 200 isin the active state, or when the size of the data in buffer 230 islarger than the remaining capacity of flash memory 250, the data fromhost 100 will be directly stored in disk 270. The HDD controller 210controls a “normal data path” related to normal write operations and a“bypass data path” related to bypass write operations. An exemplarystructure for HDD controller 210 will now be described in someadditional detail.

FIG. 8 is a block diagram further illustrating HDD controller 210.Referring to FIG. 8, HDD controller 210 comprises a flash controller215, a data manager 250, a disk controller 217, an ECC 218, and a servocontroller 219.

Flash controller 215 controls the data write/read operations to/fromflash memory 250. As is well understood by those skilled in the art, adata erase operation must be preceded a data write operation to flashmemory 250, and data written to flash memory 250 has a larger unit sizethan data erased therefrom. This makes it difficult not only to useflash memory 250 as a main memory, but also to utilize a file system fora general hard disk where flash memory 250 is used as an auxiliary ortemporary memory. Accordingly, in order to conceal the data eraseoperation required by flash memory 250, flash controller 215 is providedwith a flash translation layer (FTL).

During the write operation to flash memory 250, the FTL functions to mapof logical addresses generated by the file system relative to thephysical addresses of flash memory 250 on which the actual eraseoperation is performed. The address mapping operation of the FTL isdescribed in, for example, in U.S. Pat. No. 5,404,485; U.S. Pat. No.5,937,425; and U.S. Pat. No. 6,381,176, the subject matter of which ishereby incorporated by reference. Generally speaking, the FTL uses anaddress mapping table for a high-speed address mapping operation. Theaddress mapping table is implemented using a relatively expensive SRAM(not shown). The FTL may be implemented in the form of hardwareindependent of host 100, or it may be implemented in the form ofsoftware, such as a device driver associated with an operating system inhost 100. Alternatively, the functionality of flash controller 215 maybe implemented in software associated with disk controller 217. Howeverspecifically implemented, flash memory 250 may be functionally viewed asa general buffer. However, where the functionality of flash controller215 is implemented in software, a load for data verification requirementmay increase. Accordingly, separate hardware, such as ECC 218, may beprovided to implement in a dedicated manner the ECC generation function.

Data manager 216 detects the type of a command received from host 100,the operating state of disk 270, the size of data stored in buffer 230,and the remaining memory capacity of flash memory 250. Thereafter, onthe basis of the detection results, data manager 216 determines whetherto process a data write/read request received from host 100 through thenormal data path or through the bypass data path. In one embodiment, itis assumed that data manager 216 exchanges data and/or messages withhost 100 through an ATA interface or a serial-ATA interface.

Disk controller 217 controls the data input/output operations to buffer230 and flash controller 215 according to the determined data path.Where flash controller 215 is not provided in the form of separatehardware within HDD 200, the function of flash controller 215 may beimplemented in the form of software residing in disk controller 217. Insuch as a case, disk controller 217 controls the data input/outputoperation of flash memory 250 in software.

Servo controller 219 controls the physical operation of HDD 200, such asthe function of a motor (e.g., a spindle motor). Although notillustrated in FIG. 7, a motor such as a servo motor 290 is providedwithin HDD 200 in order to rotate disk 270 during read/write operations.

FIG. 9 is a flowchart further illustrating a method of inputting data toand outputting data from HDD 200 according to one embodiment of theinvention. Specifically, FIG. 9 exemplarily a data processing operationrelative to one exemplary command and is indicative of other commands.Exemplary method steps are indicated in parentheses.

Referring to FIG. 9, HDD 200 first receives a command from host 100(3100), and determines the type of the command (3200). If the command isdetermined to be a write command (WRITE_CMD) (3200), HDD 200 nextdetermines whether or not disk 270 is in the active state (3300).

If the disk is not in the active state, HDD 200 determines whether ornot the size (DATA_W ) of the write data is smaller than the remainingmemory capacity (FLASH_FR) of flash memory 250 (3400). If the size(DATA_W) is smaller than the remaining memory capacity (FLASH_FR), HDD200 writes the corresponding data to flash memory 250 (3510).Thereafter, HDD 200 determines whether or not flash memory 250 is full(3530). If flash memory 250 is full, HDD 200 transfers the stored datain flash memory 250 to disk 270 (3550). As described above, the datawrite operation performed when disk 270 is not in the active state iscalled the normal write operation. During the normal write operation,flash memory 250 stores a part of the data received from host 100 andsimultaneously stores the stored data into disk 270.

Returning now to method steps (3300 and 3400) in the flowchart, if disk270 is in the active state or if the size (DATA_W) is larger than theremaining memory capacity (FLASH_FR) of flash memory 250, the datareceived from host 100 is directly written to disk 270 (3600). Asdescribed above, the data write operation performed when the disk is inthe active state is called the bypass write operation. During the bypasswrite operation, the data from host 100 are directly written to disk270.

Alternatively, if the command is determined to be a read command(READ_CMD) (3200), HDD 200 determines whether or not the requested datais stored in flash memory 250 (3700). If the requested data is stored inflash memory, HDD 200 reads the corresponding data from flash memory 250(3800). As described above, the operation of reading data from flashmemory 250 is called the normal read operation.

However, if the requested data is not stored in flash memory 250, HDD200 reads the corresponding data from disk 270 (3900). As describedabove, the operation of directly reading data from disk 270 is calledthe bypass read operation.

As described above, data processing apparatus 300 incorporating HDD 200processes data implicated by a command from host 100, and collectivelyand simultaneously stores processed data to disk 270. Accordingly, it ispossible to reduce an occurrence ratio of the active state, whichconsumes a large amount of power, relative to the overall operationstate of HDD 200, thereby reducing the power consumption of HDD 200within operation of data processing apparatus 300. As flash memory 250retains data written to its memory cell even when external power isturned OFF, data recoverability is excellent. Because power consumptionis reduced, the battery life a mobile device incorporating the HDD maybe extended. These benefits and others arise from the efficientprovision of data input/output path(s) by embodiments of the inventionin accordance with the operating state of the data storage device.

It will be apparent to those skilled in the art that variousmodifications and variations may be made in the foregoing embodiments.Thus, it is intended that the scope of the invention cover suchmodifications and variations and their equivalents. The scope of theinvention rather than being limited to only the foregoing is defined bythe following claims.

1. A hard disk drive comprising: a disk; a first buffer adapted totemporarily store data to be stored on the disk; a second buffer adaptedto store data received from at least the first buffer; and, a controlleradapted to provide the data temporarily stored in the first buffer to atleast one of the disk and the second buffer in accordance with anoperating state for the disk.
 2. The hard disk drive of claim 1, whereinthe second buffer comprises nonvolatile memory adapted to store datareceived from the first buffer and further adapted to provide the storeddata to the disk.
 3. The hard disk drive of claim 1, wherein theoperating states comprise at least one of; an active state, a standbystate, an idle state, and a sleep state.
 4. The hard disk drive of claim3, wherein the controller comprises a data manager adapted to detect atleast one of; the operating state of the disk, an amount of data storedin the first buffer, and a remaining memory capacity for the secondbuffer.
 5. The hard disk drive of claim 4, wherein data temporarilystored in the first buffer is directly stored on the disk when the diskis operating in the active state.
 6. The hard disk drive of claim 4,wherein data temporarily stored in the first buffer is stored in secondbuffer when the disk in operating in the idle state and the standbystate, provided the detected remaining memory capacity for the secondbuffer is greater than the size of the data temporarily stored in thefirst buffer.
 7. The hard disk drive of claim 4, wherein the controlleris further adapted to read requested data stored on the disk and in thesecond buffer in accordance with the operating state of the disk.
 8. Thehard disk drive of claim 7, wherein the controller reads the requesteddata from the disk when the disk in operating in the active state. 9.The hard disk drive of claim 7, wherein the controller reads therequested data from the second buffer when the disk is operating in theidle state and the standby state, provided the requested data is storedin the second buffer, else reading the requested data from the disk. 10.A data processing apparatus comprising: a host adapted to generate awrite request and a read request; and a hard disk drive adapted to writedata in response to the write request and read data in response to theread request through a normal data path or a bypass data path inaccordance with an operating state for the hard disk drive.
 11. The dataprocessing apparatus of claim 10 wherein the hard disk drive comprises;a disk, a first buffer adapted to temporarily store data to be stored onthe disk, a second buffer adapted to store data received from at leastthe first buffer, and a controller adapted to provide the datatemporarily stored in the first buffer to at least one of the disk andthe second buffer in accordance with an operating state for the disk.12. The data processing apparatus of claim 11, wherein the second buffercomprises nonvolatile memory adapted to store data received from thefirst buffer and further adapted to provide the stored data to the disk.13. The data processing apparatus of claim 11, wherein the operatingstates comprise at least one of; an active state, a standby state, anidle state, and a sleep state.
 14. The data processing apparatus ofclaim 13, wherein the controller comprises a data manager adapted todetect at least one of; the operating state of the disk, an amount ofdata stored in the first buffer, and a remaining memory capacity for thesecond buffer.
 15. The data processing apparatus of claim 14, whereindata temporarily stored in the first buffer is directly stored on thedisk when the disk is operating in the active state.
 16. The dataprocessing apparatus of claim 14, wherein data temporarily stored in thefirst buffer is stored in second buffer when the disk is operating inthe idle state and the standby state, provided the detected remainingmemory capacity for the second buffer is greater than the size of thedata temporarily stored in the first buffer.
 17. The data processingapparatus of claim 14, wherein the controller is further adapted to readrequested data stored on the disk and in the second buffer in accordancewith the operating state of the disk.
 18. The data processing apparatusof claim 17, wherein the controller reads the requested data from thedisk when the disk is operating in the active state.
 19. The dataprocessing apparatus of claim 17, wherein the controller reads therequested data from the second buffer when the disk is operating in theidle state and the standby state, provided the requested data is storedin the second buffer, else reading the requested data from the disk. 20.A method for writing data to and reading data from a hard disk drivecomprising a disk, the method comprising: storing data received from ahost in a first buffer; detecting an operating state for the disk; andstoring the data in the first buffer in at least one of a second bufferand the disk in accordance with the detected operating state.
 21. Themethod of claim 20, wherein the second buffer comprises nonvolatilememory adapted to store data received from the first buffer and furtheradapted to provide the stored data to the disk.
 22. The method of claim21, wherein the operating states comprise at least one of; an activestate, a standby state, an idle state, and a sleep state.
 23. The methodof claim 22, wherein storing the data in the first buffer comprises:storing the data in the first buffer on the disk upon detecting anactive state.
 24. The method of claim 23, further comprising: afterstoring the data in the first buffer on the disk, storing the datastored in the second buffer on the disk.
 25. The method of claim 21,further comprising: detecting an amount of data stored in the firstbuffer and a remaining memory capacity for the second buffer.
 26. Themethod of claim 25, wherein storing the data in the first buffercomprises: storing the data in the first buffer in the second bufferupon detecting the idle state or the standby state, provided thedetected remaining memory capacity for the second buffer is greater thanthe size of the data temporarily stored in the first buffer.
 27. Themethod of claim 21, further comprising: reading data from the disk andthe second buffer in accordance with the detected operating state. 28.The method of claim 27, wherein data is read from the disk upondetecting the active state.
 29. The method of claim 27, wherein data isread from the second buffer upon detecting the idle state or the standbystate, provided the data is stored in the second buffer, else readingthe data from the disk.
 30. A method of reading/writing data within adata processing apparatus, the method comprising: generating a dataread/write request; and reading the data from or writing the data to ahard disk drive in response to the read/write request; wherein the datais read from or written to the hard disk drive through a normal datapath or a bypass data path in accordance with an operating state of thehard disk drive.
 31. The method of claim 30, wherein writing the data tothe hard disk comprises: storing the data in a first buffer; detectingthe operating state; and storing the data in the first buffer in one ofa second buffer and the disk in accordance with the detected operatingstate.
 32. The method of claim 31, wherein storing the data in the firstbuffer in the second buffer comprises storing the data through thenormal data path; and, wherein storing the data in the first buffer onthe disk comprises storing the data through the bypass data path. 33.The method of claim 32, wherein upon detecting an active state, storingthe data in the first buffer on the disk.
 34. The method of claim 32,further comprising: detecting an amount of data in the first buffer anda remaining memory capacity for the second buffer; and wherein upondetecting a standby state or an idle state, storing the data in thefirst buffer in the second buffer, provided the remaining memorycapacity for the second buffer is greater than the amount of data in thefirst buffer.
 35. The method of claim 30, wherein reading the data fromthe hard disk comprises: reading the data from the disk upon detectingan active state.
 36. The method of claim 35, wherein reading the datafrom the hard disk comprises: reading the data from the second bufferupon detecting an idle state or a standby state, provided the data isstored in the second buffer, else reading the data from the disk.